Heretofore, guayule plants were subjected to various separation methods and processes whereby generally resin, rubber, or both were obtained. However, no process is known wherein the guayule rubber was fractionated into various molecular weight distributions.
U.S. Pat. No. 2,390,860 to Williams relates to purification of natural rubber plants via agitation utilizing a resin solvent having a rubber solvent therein. However, the amount of rubber solvent utilized therein is such that the mixture is not a rubber solvent. As a guideline, it is stated that the solvent mixture contains approximately three parts of a non-rubber solvent to about one part of a rubber solvent. Accordingly, this patent is not pertinent in that it fails to disclose any fractionation of the rubber portion from a solvent system, and the like.
U.S. Pat. No. 2,572,046 to Meeks et al relates to a process for recovering parthenyl cinnamate and essential oils from guayule resin. Generally, a two-phase solvent system is utilized wherein one phase contains a water-miscible organic solvent and the remaining phase is a hydrocarbon solvent. Usually a large amount of the miscible organic solvent is utilized. No disclosure is made of fractionating any rubber extraction to obtain a particular molecular weight distribution thereof.
U.S. Pat. No. 2,618,670 to Clark relates to a process for deresinating rubber from plants wherein partially water-miscible resin solvent is utilized such as methyl ethyl ketone. Although guayule rubber-bearing material is separated from a mixture containing the solvent, water, and guayule plants, no disclosure is made of fractionating a portion of said rubber material, or the like.
U.S. Pat. No. 4,376,835 to Kay and Gutierrez relates to a process for processing guayule plant material. U.S. Pat. No. 4,405,532 to Gutierrez, Kay and Serbin relates to a method of storing guayule material. U.S. Pat. No. 4,435,337 to Kay and Gutierrez relates to a process for extracting rubber and byproducts from guayule material. However, none of these patents disclose fractionating a portion of the guayule rubber material.